We hope to elucidate the role of the histones in the tissue-specific modification of gene inducibility which is thought to be the molecular basis for cell differentiation and possibly carcinogenesis by investigating: a) The primary structure of the histone variants and the minor histones species resolved by polyacrylamide gel electrophoresis in the presence of nonionic detergents; b) The relation between changes in the histone complement and the functional specialization of cells; c) The distribution of the histone variants and the minor histone species in the chromosomes, especially with respect to active and inactive regions; d) The interactions of different histone components with other chromosomal constituents, such as DNA, other histones and nonhistone proteins. BIBLIOGRAPHIC REFERENCES: Borun, T. W., Gabrielli, F., Ajiro, K., Zweidler, A., and Baglioni, C. Further evidence of transcriptional and translational control of histone messenger RNA during the HeLa S-3 cell cycle. Cell 4:59-67, 1975. Cohen, L.H. and Zweidler, A. Switches in the synthesis of histones during embryogenesis. Fed. Proc. 34:611a, Abstract, 1975.